This is a competing renewal application from the Center for Hearing and Balance at Johns Hopkins University School of Medicine for a Research Core Grant from the National Institute for Deafness and Other Communication Disorders. The Center includes 16 investigators drawn from the Departments of Otolaryngology-Head and Neck Surgery, Biomedical Engineering, Neuroscience, Neurology, and Molecular Biology and Genetics. These laboratories provide a Research Base of 20 R01 awards, 14 of them from the NIDCD, with scientific aims ranging from the molecular biophysics of hair cells to behavioral assays of hearing and balance. Three Research Cores are proposed that will facilitate ongoing research and stimulate new initiatives at the interface between existing programs. 1. The Engineering Core will develop and distribute advanced data acquisition and signal analysis software, and provide general hardware and software support for Center laboratories. 2. The Histology Core will provide technical assistance and material support for light and electron microscopic studies, including access to microtomes and cryotomes for Users. Ultra-thin sectioning and EM analysis will be provided by a half-time senior histologist. Also, Users will receive guidance in tissue preparation, sectioning, and visualization techniques. Fluorescence microscopy will be available through a fluorescence microscope and digital imaging station in the Core. 3. The Neurophysiology Core will develop and distribute advanced CMS recording methods for use in freely-behaving animals. Indwelling multi-electrode arrays will be implemented and applied with the assistance of Core staff. 4. In addition, an Administrative unit will oversee operations throughout the Cores, organize the Center's speakers program, provide clerical and personnel support, and prepare reports.